Transcriptomics and proteomics analyses reveal the molecular mechanisms of yeast cells regulated by Phe-Cys against ethanol-oxidation cross-stress.

Antioxidant dipeptide Phe-Cys (FC) could dramatically improve yeast cells resistance to ethanol-oxidation cross-stress, but the regulatory mechanisms remain unclear. Therefore, transcriptomic and proteomic analyses were conducted to investigate the effects of FC treatment on yeast under ethanol-oxidation cross-stress. Following FC supplementation, 875 differential expressed genes (DEGs) and 1296 differential expressed proteins (DEPs) were identified. Integrated analysis revealed a substantial enrichment of DEGs and DEPs in the KEGG pathways of carbon metabolism, amino acid biosynthesis, cofactor biosynthesis, and glycolysis/gluconeogenesis. Furthermore, FC improved yeast cell membrane integrity by promoting fatty acids and steroids biosynthesis, and implemented a high-energy strategy by upregulating glycolysis and oxidative phosphorylation. Additionally, alterations in DEGs and DEPs levels associated with amino acids metabolism accelerated protein synthesis and enhanced cell viability. In conclusion, this study elucidated the response mechanisms of yeast to FC treatment under ethanol-oxidation cross-stress, providing a theoretical basis for the application of FC in high-gravity brewing.

Antioxidant Dipeptides Enhance Osmotic Stress Tolerance by Regulating the Yeast Cell Wall and Membrane.

This study aimed to investigate the role of the yeast cell wall and membrane in enhancing osmotic tolerance by antioxidant dipeptides (ADs) including Ala-His (AH), Thr-Tyr (TY), and Phe-Cys (FC). Results revealed that ADs could improve the integrity of the cell wall by restructuring polysaccharide structures. Specifically, FC significantly (p < 0.05) reduced the leakage of nucleic acid and protein by 2.86% and 5.36%, respectively, compared to the control. In addition, membrane lipid composition played a crucial role in enhancing yeast tolerance by ADs, including the increase of cell membrane integrity and the decrease of permeability by regulating the ratio of unsaturated fatty acids. The up-regulation of gene expression associated with the cell wall integrity pathway (RLM1, SLT2, MNN9, FKS1, and CHS3) and fatty acid biosynthesis (ACC1, HFA1, OLE1, ERG1, and FAA1) further confirmed the positive impact of ADs on yeast tolerance against osmotic stress.

Biological Functions of Antioxidant Dipeptides.

In the history of modern nutritional science, understanding antioxidants is one of the major topics. In many cases, food-derived antioxidants have π conjugate or thiol group in their molecular structures because π conjugate stabilizes radical by its delocalization and two thiol groups form a disulfide bond in its antioxidative process. In recent years, antioxidant peptides have received much attention because for their ability to scavenge free radicals, inhibition of lipid peroxidation, chelation of transition metal ions, as well as their additional nutritional value. Among them, dipeptides are attracting much interest as post-amino acids, which have residues in common with amino acids, but also have different physiological properties and functions from those of amino acids. Especially, dipeptides containing moieties of several amino acid (tryptophan, tyrosine, histidine, cysteine, and methionine) possess potent antioxidant activity. This review summarizes previous details of structural property, radical scavenging activity, and biological activity of antioxidant dipeptide. Hopefully, this review will help provide a new insight into the study of the biological functions of antioxidant dipeptides.